Multistage polymerization process using a catalyst having different catalytically active sites

ABSTRACT

The invention relates to a process for the preparation of an olefin polymer wherein olefin polymerization is effected in a plurality of polymerization reaction stages in the presence of an olefin polymerization catalyst material, characterized in that said catalyst material comprises at least two different types of active polymerization sites.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of the U.S. designation ofInternational Application No. PCT/GB98/01756, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to a process of addition polymerization,especially olefin polymerization, and in particular to a multistagepolymerization process effected using a multi-site polymerizationcatalyst.

The molecular weight distribution (MWD) of a polymer affects theproperties of the polymer, in particular its mechanical strength andprocessability. Mechanical strength to a large extent is determined bythe high molecular weight fraction and processability to a large extentis determined by the low molecular weight fraction. The mechanicalstrength moreover can be manipulated by the inclusion of n-olefincomonomers, with it thus being possible to vary the nature and relativecontent of the side chains so introduced. This is particularly importantfor the high molecular weight portion of the broad MWD polymer, e.g. aPE polymer, and thus the comonomer content of the high molecular weightportion may typically be greater than that in the low molecular weightportion which latter may be a homopolymer. Accordingly polymers with abroad or multimodal (e.g. bimodal) MWD find many uses as for example inblow moulding, films, pipes, etc., where a combination of strength andprocessability is particularly important.

Certain olefin polymerization catalysts are generally less suitable forthe single stage preparation of polymers for such uses because the MWDfor the polymers they produce is too narrow and as a result the polymermay be difficult to process.

The preparation of broad MWD olefin polymers is described for example inEP-A-310734, EP-A-128045 and NO-923334.

BRIEF SUMMARY OF THE INVENTION

Thus broad MWD olefins can be made in a dual reactor system (e.g. asdescribed in NO-923334) using a variety of transition metal catalysts,e.g. Ziegler catalysts. The broad MWD results in this case from theprocessing conditions in the different reactors favouring the productionof different molecular weight polymers, e.g. one favouring theproduction of a higher molecular weight polymer and a second favouringproduction of a lower molecular weight polymer. Broad MWD polyolefinsmay also be produced in a single reactor using either catalyst mixturesor multisite catalysts, ie. within the same process conditions thedifferent catalysts or different catalytic sites favour production ofpolymers of different molecular weights. This arises since the differentcatalytic sites may have significantly different propagation/terminationrates for olefin polymerization (see for example EP-A-310734).

In addition to being used in processes with essentially a singlereactor, such multisite catalysts may be used in processes with severalreactors, for example, where the reactor conditions are so adjusted thatpolymers with approximately the same characteristics are made in severalof these reactors.

We have now found that the MWD of a polyolefin can be particularlyeffectively tailored to suit the needs of the user of the polyolefin,e.g. the producer of blow moulded objects, cables, tubes and pipes,etc., if polymerization is effected in at least two reaction stagesusing a catalyst material, generally a particulate material, thatcontains at least two different types of active polymerization sites.Typically such a catalyst material may contain a particulate multi-sitecomponent together with, in a liquid phase, co-catalysts and adjuvants.

Thus viewed from one aspect the invention provides a process for thepreparation of an olefin polymer wherein olefin polymerization iseffected in a plurality of polymerization stages, optionally in aplurality of polymerization reactors, in the presence of an olefinpolymerization catalyst material, characterized in that said catalystmaterial comprises at least two different types of active polymerizationsites.

The reactor used in one stage of the process may be used in a subsequentpolymerization stage. Where the process of the invention is effected ina single reactor vessel, polymerization stages will conveniently beeffected using different monomer/comonomer mixtures and optionallydifferent process conditions (ie. temperature, pressure, reaction time,etc.).

It is particularly preferred that no one of the reaction stages used inthe process of the invention be used to produce more than 95% by weightof the overall polymer, more particularly no more than 90%, especiallyno more than 85%, more especially no more than 78% and most especiallyno more than 70%. Thus if a prepolymerization is effected to produce acatalyst-polymer material for use in the process of the invention, thatprocess will generally involve the use of at least two more reactionstages, such stages producing more than 93% by weight, preferably morethan 96% by weight, particularly preferably more than 98% by weight ofthe polymer material. In the absence of prepolymerization, the processof the invention will involve at least two reaction stages capable ofproducing up to and including 100% by weight of the polymer material.Preferably however, at least 10% by weight of the total polymer shouldbe made in each stage.

Furthermore it is especially preferred that at least two differentreactants selected from monomer, comonomer and hydrogen be used in atleast two of the reaction stages whereby at least one of the catalyticsites is caused to produce a different polymer in two different reactionstages. In this way, the tailoring of the high molecular weight end ofthe molecular weight distribution discussed below can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a graph comparing the apparent viscosity vs. apparentshear for the products of Example 1 (invention) and Example 2(comparative);

FIG. 2 depicts a graph showing the weight fraction vs. molecular weightfor 30091HEL;

FIG. 3 depicts a graph showing the weight fraction vs. molecular weightfor 21046;

FIG. 4 depicts a graph showing the weight fraction vs. molecular weightfor 21051HEL;

FIG. 5 depicts a graph showing the weight fraction vs. molecular weightfor 21129HEL;

FIG. 6 depicts a graph showing the weight fraction vs. molecular weightfor 30092HEL;

FIG. 7 depicts a graph showing the weight fraction vs. molecular weightfor 21003;

FIG. 8 depicts a graph showing the weight fraction vs. molecular weightfor 21044;

FIG. 9 depicts a graph showing the weight fraction vs. molecular weightfor 21016;

FIG. 10 depicts a graph comparing the weight fraction vs. molecularweight for the compounds of FIGS. 2-9;

FIG. 11 depicts a graph comparing the weight fraction vs. molecularweight for PP5671, PP5659, and PP5715;

FIG. 12 depicts a graph comparing the weight fraction vs. molecularweight for PP5672, PP5649, and PP5664; and

FIG. 13 depicts a graph comparing the weight fraction vs. molecularweight for PP5772, PP5571, PP5749 and PP5664.

DETAILED DESCRIPTION OF THE INVENTION

In each reaction stage, the different types of active polymerizationsites on the catalyst material will generate polymers of differentmolecular weight distribution, in other words the resulting polymer willbe an intimately mixed polymer mixture, e.g. having a multimodal orbroad molecular weight distribution or otherwise containing twointermingled populations of polymers with different properties. By usinga multiplicity of polymerization reactors a control of a multimodalmolecular weight distribution may be achieved using the process of theinvention which cannot be achieved in a single reactor using a catalystsystem even with four or more active polymerization sites.

The process of the invention involves effecting polymerization in aplurality of (i.e. at least two) reaction stages. The reactors used maybe conveniently be any of the conventionally used polymerizationreactors, e.g. reactors for solution polymerization, slurry tank orslurry loop polymerization or gas phase polymerization, etc. The polymerproduct of an early stage (e.g. the first) may be passed on to thesubsequent (e.g. second) reactor on a continuous, semi-continuous orbatchwise basis. In a semi-continuous process, a batch of the reactionmixture is extracted from one reactor and passed to the next reactor ata regular interval which is less than the overall average residence timefor the first reactor, e.g. batches may be removed every minute eventhough the overall residence time is one hour. Each reactor willconveniently be provided with means for supplying monomer into thereactor and the overall multi-reactor structure will preferably beprovided with means for recycling diluents, fluidizing gas or monomerinto one or more of the individual reactors. Typically the process ofthe invention will be a multistage solution polymerization process or aprocess using a combination of two or more of the reactor typesmentioned above, e.g. a combination of a loop and a gas-phase reactorsuch as that described in Norwegian Patent Application No. 923334.Preferably the process of the invention should use only particle formingreactors such as slurry and gas phase reactors or solution phasereactors. The total number of reactors used will depend on the catalystsystem used and the molecular weight distribution desired for thepolymer end product. Typically 2 to 5, preferably 2 or 3, mostpreferably 2 reactors will be used.

For slurry reactors, the reaction temperature will generally be in therange 60 to 110° C. (e.g. 85-110° C.), the reactor pressure willgenerally be in the range 5 to 80 bar (e.g. 25-65 bar), and theresidence time will generally be in the range 0.3 to 5 hours (e.g. 0.5to 2 hours). The diluent used will generally be an aliphatic hydrocarbonhaving a boiling point in the range −70 to +100° C. In such reactors,polymerization may if desired be effected under supercriticalconditions, especially in loop reactors.

For gas phase reactors, the reaction temperature used will generally bein the range 60 to 115° C. (e.g. 70 to 110° C.), the reactor pressurewill generally be in the range 10 to 25 bar, and the residence time willgenerally be 1 to 8 hours. If the gas phase reactor is not the firstreactor to be used in the process, the residence time can be furtherdecreased to 0.25 hours. The gas used will commonly be a non-reactivegas such as nitrogen together with monomer (e.g. ethylene or propylene).

For solution phase reactors, the reaction temperature used willgenerally be in the range 130 to 27° C., the reactor pressure willgenerally be in the range 20 to 400 bar and the residence time willgenerally be in the range 0.1 to 1 hour. The solvent used will commonlybe a hydrocarbon with a boiling point in the range 80-200° C.

The process of the invention is for the polymerization of olefins, inparticular alpha-olefins and mixtures thereof, e.g. C₂₋₁₀ α-olefins suchas ethylene, propene, but-1-ene, n-hex-1-ene, 4-methyl-pent-1-ene,n-oct-1-ene, etc. The process is particularly effective for thepreparation of polyethylene and polypropylene as well as copolymers ofethylene with one or more copolymerizable monomers, e.g. C₃₋₂₀ mono anddienes, more preferably C₃₋₁₀ α-olefin monomers and copolymers ofpropene with one or more copolymerizable monomers, e.g. C₄₋₂₀ mono anddienes, more preferably C₄₋₁₀ α-olefin monomers or ethylene.

The process of the invention is particularly suited to producingpolypropylene homopolymers, polypropylene random copolymers, thehomopolymer component of a heterophasic copolymer which also includepolymers with high ethylene content such as ethylene/propylene rubberand low density polyethylene.

Preferably the polymer product has ethylene as the major monomer, ie. atleast 50% by number monomer residues being of ethylene, more preferablyat least 50% by weight being ethylene residues.

The catalyst material used in the method of the invention ischaracterized by having different types of active polymerization siteshaving a significantly different ratio between propagation andtermination rates for olefin polymerization and/or different degree oftacticity (for polypropylene) and/or different degree of incorporationof comonomer. The catalyst material thus conveniently comprises at leasttwo different catalysts. These can be selected from all types ofcatalysts capable of olefin polymerization, e.g. Ziegler catalysts(which term encompasses Ziegler-Natta catalysts), metallocene catalysts,chromium catalysts and other organometallic or coordination catalystsand the different catalysts may be of the same or different types, e.g.Ziegler plus metallocene, metallocene plus metallocene, Ziegler plusZiegler, organometallic plus metallocene, etc. Preferably the catalystcomprises two or more cyclopentadienyl-containing organometalliccompounds, e.g. metallocenes.

Where one catalysts type in the catalyst material used in the process ofthe invention is a Ziegler catalyst it is especially preferred that atleast one non-Ziegler catalyst type also be present, e.g. a metallocene.

The catalyst material may include one or more cocatalysts, catalystactivators or catalyst precursors, ie. the catalyst material may containsubstances which react together to create a substance possessing theactive polymerization site. Examples of these co-catalysts, catalystactivators and catalyst precursors include aluminium trialkyls (e.g.triethylaluminium), aluminoxanes such as methylaluminoxane, cationicactivators such as boron containing compounds, transition metalcompounds (e.g. halogenide compounds), magnesium compounds, group IIorganometallic compounds, e.g. aluminium or boron based compounds. Suchmaterials may be solids, liquids or may be in solution in a liquid phaseof the catalyst material which may be a solution, a solid, a dispersion,a suspension, a slurry, etc.

Preferred aluminoxanes include C₁₋₁₀ alkyl aluminoxanes, in particularmethyl aluminoxane (MAO) and aluminoxanes in which the alkyl groupscomprise isobutyl groups optionally together with methyl groups. Suchaluminoxanes may be used as the sole co-catalyst or alternatively may beused together with other co-catalysts. Thus besides or in addition toaluminoxanes other cation complex forming catalyst activators may beused. In this regard mention may be made of the silver and boroncompounds known in the art. What is required of such activators is thatthey should react with the η-liganded complex to yield an organometalliccation and a non-coordinating anion (see for example the discussion onnon-coordinating anions J in EP-A-617052 (Asahi)).

Aluminoxane co-catalysts are described by Hoechst in WO 94/28034. Theseare linear or cyclic oligomers having up to 40, preferably 3 to 20, [Al(R″)O] repeat units (where R″ is hydrogen, C₁₋₁₀ alkyl (preferablymethyl and/or isobutyl) or C₆₋₁₈ aryl or mixtures thereof).

The catalyst material may be introduced into the first of the reactorsused in the process of the invention as a single material containing allthe components of the catalyst material or as two or more materialswhich together contain all of the components of the catalyst material orwhich together interact to generate the catalyst material. It ispreferred to introduce the catalyst material as a single material whichmay be a solution, a solid, a dispersion, a suspension or a slurry, etc.

The catalyst material may if desired include a support, e.g. aninorganic or organic carrier material, preferably a solid particulatematerial and also preferably a porous material. Conventional catalystsupport materials may be used in this regard, e.g. porous inorganic ororganic materials, for example oxides such as silica, alumina,silica-alumina, silica with Ti, zirconia, etc., non-oxides such asmagnesium halides, e.g. MgCl₂, aluminium phosphate, zeolites etc, andpolymers such as polystyrene, polymethacrylate,polystyrene-divinylbenzene and polyolefins such as polyethylene andpolypropylene.

Where an inorganic support material is used, this will preferably betreated, e.g. thermally or chemically to remove surface hydroxyl.

Where a support material is used, this will especially preferably beused to carry more than one type of catalytic site, ie. so that aparticulate support will present two or more different activepolymerization sites on the same particles.

Where different types of catalytic sites are present on the same carrierparticles, it is preferred that the ratio between the different types ofsite be substantially uniform within the particles, ie. it is preferredthat the ratio be the same on the surface as it is at different depthswithin the particles and that the ratio be substantially uniform betweenthe particles.

Where a co-catalyst or catalyst activator is used, it will be especiallypreferred to have the activated catalyst system loaded onto aparticulate support. Alternatively but less preferably the activatablecatalytic site may be loaded onto a particulate support which is placedin a solution of the co-catalyst or activator.

Where co-catalysts or catalyst activators for different catalysts areused, it is preferred to load these and the catalysts onto a supportsimultaneously rather than sequentially. In this way the apparatus usedis used more efficiently and the total time required for preparing thesupported catalyst is reduced since sequential impregnation have atime-consuming further impregnation step. Sequential impregnation isthus a more complicated process and disadvantageously requires the useof more solvent. Moreover, in this way the catalysts and co-catalysts oractivators are distributed more uniformly (relative to each other) inthe support. As a result, properties of the resulting polymer productsare enhanced.

More particularly the simultaneous loading of different catalysts upon asupport results in the production, in a subsequent single or multistagepolymerization, of a reactor powder (the polymer product of thepolymerization process) which has good interparticle homogeneity, and abroad, e.g. bimodal, MWD. More especially, the homogeneity achieved isbetter than that achievable by simply using a mixture of supportedcatalysts, each carrying a single catalyst system, and thesimultaneously multiply (e.g. dually) impregnated catalysts have highactivity in terms of polymer production.

Viewed from a further aspect therefore the invention provides a processfor the preparation of a supported catalyst, said process comprisingcontacting a porous particulate support material (e.g. silica, alumina,zirconia, magnesium chloride, etc.) with a solution comprising at leasttwo different catalytically active materials or precursors therefor(e.g. procatalysts) and optionally comprising at least one co-catalystor catalyst activator, and recovering said support material impregnatedwith said catalytically active materials or precursors or reactionproducts thereof with said co-catalyst or catalyst activator, preferablywherein the liquid content of said solution and said support materialbefore contact thereof with said solution is less than 1.4, morepreferably less than 1.2, most preferably less than 1.0 times the porevolume of said support material.

In this process, the support material may be used while it is partiallyimpregnated with a non-aqueous liquid, e.g. a hydrocarbon (preferably asaturated or aromatic hydrocarbon). At least one, and preferably atleast two of the catalysts or procatalysts preferably compriseη-liganded complexes as discussed herein.

The η-liganded complexes may be used together with Lewis acids,Bronstedt acids or Pearson acids, or additionally in the presence ofLewis bases.

Such Lewis acids are, for example, boranes or alanes, such as aluminiumalkyls, aluminium halogenides, aluminium alkoxides, boron organyles,boron halogenides, boron acid esters or boron or aluminium compoundswhich contain both halogenide and alkyl or aryl or alkoxidesubstituents, and also mixtures thereof or the triphenylmethyl cation.Especially preferred are aluminium oxanes or mixtures ofaluminium-containing Lewis acids with water. All acids work as ionisingagents, according to modern knowledge, which form a metalloceniumcation, load-compensated by a bulky, badly coordinating anion.

Furthermore, the invention relates to the reaction products of suchionising agents with η-liganded complexes.

Examples of such badly coordinating anions are, e.g. B(C₆H₅)₄ ^(θ),B(C₆F₅)₄ ^(θ), B(CH₃)(C₆F₅)₃ ^(θ),

or sulphonates such as tosylate or triflate, tetrafluoroborates,hexafluorophosphates or antimonates, perchlorares, and also voluminouscluster molecule anions of the type of the carboranes, for exampleC₂B₉H₁₂ ^(θ) or CB₁₁H₁₂ ^(θ). If such anions are present, metallocenecompounds can also work as highly-effective polymerisation catalystseven in the absence of aluminium oxane. This is primarily the case if anX-ligand represents an alkyl group or benzyl. However, it can also beadvantageous to use such metallocene complexes with voluminous anions incombination with aluminium alkylenes such as (CH₃)₃Al, C₂H₅)₃Al,(n-/i-propyl)₃Al, (n-/t-butyl)₃Al, (i-butyl)₃Al, the isomers pentyl,hexyl or octyl aluminium alkyl, or lithium alkylenes such as methyl-Li,benzyl-Li, butyl-Li or the corresponding Mg-organic compounds, such asGrignard compounds or Zn-organyls on the one hand, such metalalkylstransfer alkyl groups to the central metal, on the other hand theycapture water or catalyst poisons from the reaction medium or monomerduring polymerisation reactions. Examples of boron compounds from whichsuch anions can be derived are:

triethylammonium-tetraphenylborate, tripropylammonium-tetraphenylborate,tri(n-butyl)ammonium-tetraphenylborate,tri(t-butyl)ammonium-tetraphenylborate N,N-dimethylanilinium-tetraphenylborate,N,N-diethylanilinium-tetraphenylborate,N,N-dimethyl(2,4,6-trimethylanilinium-tetraphenylborate,trimethylammonium-tetrakis(pentafluorophenyl)borate,triethylammonium-tetrakis(pentafluorophenyl)borate,tripropylammonium-tetrakis(pentafluorophenyl)borate,tri(n-butyl)ammonium-tetrakis(pentafluorophenyl)borate,tri(sec-butyl)ammonium-tetrakis(pentafluorophenyl) borate,N,N-dimethylanilinium-tetrakis(pentafluorophenyl)borate,N,N-diethylanilinium-tetrakis(pentafluorophenyl)borate,N,N-dimethyl(2,4,5-trimethylanilinium-tetrakis(pentafluorophenyl)borate,trimethylammonium-tetrakis(2,3,4,6-tetrafluorophenyl)borate,triethylammonium-tetrakis(2,3,4,6-tetrafluorophenyl)borate,tripropylammonium-tetrakis(2,3,4,6-tetrafluorophenyl)borate,tri(n-butyl)ammonium-tetrakis(2,3,4,6-tetrafluorophenyl)-borate,dimethyl)(t-butyl)ammonium-tetrakis(2,3,4,6-tetrafluorophenyl)-borate,N,N-dimethylanilinium-tetrakis(2,3,4,6-tetrafluorophenyl)-borate,N,N-diethylanilinium-tetrakis(2,3,4,6-tetrafluorophenyl)-borate,N,N-dimethyl-(2,4,6-trimethylanilinium)-tetrakis-(2,3,4,6-tetrafluorophenyl)-borate,dialkylammonium salts, such as:

di-(i-propyl)ammonium-tetrakis(pentafluorophenyl)-borate anddicyclohexylammonium-tetrakis(pentafluorophenyl)borate; tri-substitutedphosphonium salts, such as:triphenylphosphonium-tetrakis(pentafluorophenyl)borate, tri(o-tolyl)phosphonium-tetrakis (pentafluorophenyl)-borate,tri(2,6-dimethylphenyl)phosphonium-tetrakis(pentafluorophenyl)-borate,triolylmethyl-tetrakis(pentafluorophenyl)borate,triphenylmethyl-tetraphenylborate(trityl-tetraphenyl-borate),trityl-tetrakis(pentafluorophenyl)borate, silver tetrafluoroborate,tris(pentafluorophenyl)borane, tris(trifluoromethyl)borane.

Co-catalysts are, for example, aluminiumoxane compounds.

These also include those of formula

wherein

R denotes C₁-C₂₀-alkyl, C₆-C₁₂-aryl or benzyl and

n is an integer from 2 to 50, preferably 10 to 35.

It is also possible to use a mixture of various aluminium oxanes or amixture of their precursors (aluminium alkyls or alkylaluminiumhalogenides) in combination with water (in gaseous, liquid, solid orbound form, also as crystallised water). The water can also be suppliedas (residual) dampness of the polymerisation medium, the monomer or acarrier such as silica gel.

The bonds which project from the square brackets of formula (XI)contain, as end groups of the oligomerous aluminium oxane, R groups orAlR₂-groups. These aluminium oxanes are generally present as a mixtureof several of themselves with different chain lengths. Fine examinationhas also revealed aluminium oxanes with ring-formed or cagelikestructure. Aluminium oxanes are commercial compounds. In the specialcase of R═CH₃, mention is made of methyl aluminium oxanes (MAO).

Other co-catalysts are aluminium alkyls, lithium alkyls or Mg-organiccompounds such as Grignard compounds or partially-hydrolysed boronorganyls. Aluminium oxanes are the preferred co-catalysts.

Activation with the co-catalyst, or production of the voluminous non- orweakly coordinating anion can take place in the autoclaves or in aseparate reaction container (pre-forming). Activation can take place inthe presence or absence of the monomers which are to be polymerised.Activation can be undertaken in an aliphatic or aromatic or halogenatedsolution or suspension medium, or on the surface of a catalyst carriermaterial.

The metallocene compounds and the aluminium oxanes can be used as suchboth in homogenous form and also individually or together in heterogenicform on carriers. Here, the carrier material can be of an anorganic ororganic nature, such as silica gel, Al₂O₃, MgCl₂, NaCl, cellulosederivatives, starches and polymers. In doing this, either themetallocene compound or the aluminium oxane can firstly be placed on thecarrier and then the other components can be added afterwards. In thesame way, the metallocene compound can activate with the aluminium oxanein homogenous or heterogenous form, after which the activatedmetallocene compound can be placed on the carrier.

Carrier materials are preferably thermically and/or chemicallypre-treated and the water content or the OH group concentration is to beset as defined or kept as low as possible. Chemical pre-treatment cane.g. comprise reaction of the carrier with aluminium alkyl. Anorganiccarriers are usually heated to 100° C. to 1000° C. for 1 to 100 hoursbefore use. The surface of such anorganic carriers, especially of silica(SiO₂) is between 10 and 1000 m²/g, preferably between 100 and 800 m²/g.Particle diameter is between 0.1 and 500 micrometers (μ), preferablybetween 10 and 200 μ.

Thus viewed from a further aspect the invention provides a process forthe preparation of a supported catalyst, said process comprisingreacting in the liquid phase (e.g. in solution) at least two η-ligandedpolymerization catalysts and a co-catalyst (e.g. an aluminoxane,preferably methylaluminoxane), and contacting the reaction product witha porous particulate support material (e.g. silica, alumina, zirconia,magnesium chloride, etc.) whereby to load said reaction product ontosaid support material. Support impregnation with the catalysts and anyco-catalysts or catalyst activators may be performed as described inWO96/00245, WO95/11264, EP-A-619325 or, more preferably, WO95/12622. Ifdesired, a prepolymerization may be effected, e.g. as described in U.S.Pat . No. 5,240,894, so that prepolymerized catalyst particles are usedin the major polymerization stage(s).

Viewed from a further aspect the invention provides a supportedcatalyst, obtainable by a process as described in the precedingparagraph, comprising a porous particulate support material (preferablyan inorganic oxide or halide or a polymer such as an acrylate) particleswhereof carry at least two η-liganded catalyst:co-catalyst reactionproducts the distribution pattern whereof within said particles issubstantially similar.

By substantially similar distribution patterns it is meant that the twoη-liganded catalyst:co-catalyst (e.g. metallocene:MAO) products areessentially intermixed within the particles (rather than having one witha pattern of distributing relatively more to the outer extremities ofthe particles than does the other).

Suitable η-liganded catalysts are described below; however theη-liganded catalyst should preferably be such that the polymers theyproduce have different properties, e.g. molecular weight distributionsor mean molecular weights. Preferably the combination used is ofunbridged and bridged bis-η-liganded complexes of group 4, 5 or 6metals, e.g. where the unbridged η-ligand complex is a metallocene withtwo homo or heterocyclopentadienyl ligands which are optionally ringsubstituted by fused or pendant substituent groups and the bridgedη-ligand complex comprises two η-liganding groups joined by a 1 to 4atom chain. One example of a metallocene combination would thus be (i)an unbridged biscyclopentadienyl Ti, Zr or Hf compound and (ii) abridged bis-indenyl Ti, Zr or Hf compound, e.g. Cp₂Zr Cl₂ andCH₂CH₂(Ind)₂Zr Cl₂ or Si(CH₃) (Ind)₂ZrCl₂. An alternative combinationwould be a dimethylsilylbis(fluorenyl) Ti, Zr or Hf complex (e.g.SiMe₂(fluorenyl) ZrCl₂) and a bis n-butylcyclopenta-dienyl Ti, Zr or Hfcomplex.

Such simultaneously loaded supported catalysts confer desirableproperties on the polymer products of the polymerization processes theyare used in. Accordingly, viewed from a further aspect, the inventionprovides a process for the preparation of an olefin polymer by acatalysed polymerization, characterized in that as a catalyst is used asupported catalyst produced by simultaneously loading at least twocatalytically effective η-liganded compounds onto a porous particulatesupport material, preferably by loading at least two η-ligandedcatalyst:aluminoxane reaction products onto said support material.

Viewed from a further aspect the invention provides an olefin polymerobtainable by the process described in the preceding paragraph, andobjects (e.g. containers, fibres, films, sheets, tubes, etc) fabricatedtherefrom.

Viewed from a yet still further aspect the invention provides the use ofa supported catalyst produced by simultaneously loading at least twocatalytically effective η-liganded catalyst compounds into a porousparticulate support material (preferably by loading at least twoη-liganded catalyst:aluminoxane reaction products onto said supportmaterial) as an olefin polymerization catalyst, preferably in a slurryphase polymerization reaction.

Such simultaneously loaded supported catalysts are preferably used inpolymerization processes wherein olefin polymerization is effected in aplurality of polymerization reaction stages. However they may also beused in single stage or single reactor polymerizations.

Thus it will be recognized that the catalyst material used in theprocess of the invention is not limited to being of certain metal typesbut instead to being a combination of catalysts with certain affinityfor comonomer incorporation and capable of producing polymers ofappropriate molecular weights under the reaction conditions in thevarious polymerization reactors used in the process of the invention.

Examples of suitable catalyst types include the Ziegler catalystsdisclosed in U.S. Pat. No. 5,151,397, the titanium and vanadiumcatalysts and zirconium metallocenes of EP-A-318048, the metallocene andaluminoxane catalysts of EP-A-206794, the mixed Ziegler-metallocenecatalysts of EP-A-447070 (e.g. comprising zirconium metallocenes,titanium and/or vanadium halides, magnesium dichloride and optionallyorgano-aluminium compounds such as aluminoxanes), the bisindenylmetallocene mixtures of EP-A-643084, the metallocenes of EP-A-69951, thebiscyclopentadienyl metallocenes of EP-A-410734, and the mixedmetallocenes and aluminoxane catalysts of EP-A-128045.

In general η-liganded metal complexes are preferred as catalysts. Byη-ligand is meant a ligand which coordinates the metal with η-orbitalelectrons. Metals may be complexed for example with 1, 2 or 3 η-ligands.Complexes of metals with two η-ligands are generally termedmetallocenes. η-liganded complexes based on zirconium, hafnium andtitanium are preferred as catalysts. The η-bonding ligands in suchcatalysts may be simple unsubstituted homo- or heterocyclopentadienylrings, but preferably they will be optionally substituted fused ringsystems (e.g. indenyl ligands), substituted cyclopentadienyl rings,optionally substituted bridged bis-cyclopentadienyl ligands oroptionally substituted bridged bis fused ring systems (e.g. bis indenylligands). Suitable examples are discussed for example in EP-B-35242(BASF), EP-B-129368 (Exxon) and EP-B-206794 (Exxon).

Examples of single site polymerization catalysts which may be includedin the catalyst material used in the process of the invention in orderto generate high molecular weight polymers include the metallocenecompounds with a one or two atom long bridge joining thecyclopentadienyl rings, e.g. a ethylene bridge or a bridge R₂X where Xis carbon or silicon and R is alkyl, aryl, aralkyl, etc. (for examplemethyl, benzyl, etc group typically containing up to 10 carbons).Preferably, a ring position on the cyclopentadienyl rings adjacent thebridge attachment position is substituted, for example by an alkyl groupsuch as methyl. The metal of the metallocene may conveniently be anygroup 3 to 6 metal, preferably zirconium or hafnium. Examples of suchmetallocenes include:

dimethyl-silyl{bis-(2-methyl-4-tert.butyl)}zirconium-dichloride;

dimethyl-silyl{bis-(2-methyl-4-phenylindenyl)}zirconium-dichloride;

dimethyl-silyl{bis-(2-methyl-4-naphthylindenyl)}zirconium-dichloride;

dimethyl-silyl{bis-(2-methyl-4,6-di-isopropylindenyl)}zirconium-dichloride;

dimethyl-silyl{bis-(2-methyl-4,7-dimethylindenyl)}zirconium-dichloride;

dimethyl-silyl{bis-(2-methyl-benz[e]-indenyl)}zirconium-dichloride;

dimethyl-silyl{bis-(fluorenyl)}zirconium-dichloride;

rac-[ethylenebis(2-(tert)-butyldimethylsiloxy)indenyl)]-zirconium-dichloride;

dimethyl-silyl{bis-(2-methyl-4-tert.butyl)}hafnium-dichloride;

dimethyl-silyl{bis-(2-methyl-4-phenylindenyl)}hafnium-dichloride;

dimethyl-silyl{bis-(2-methyl-4-naphthylindenyl)}hafnium-dichloride;

dimethyl-silyl{bis-(2-methyl-4,6-di-isopropyl-indenyl)}hafnium-dichloride;

dimethyl-silyl{bis-(2-methyl-4,7-dimethyl-indenyl)}hafnium-dichloride;

dimethyl-silyl{bis-(2-methyl-benze[e]indenyl)}hafnium-dichloride;

dimethyl-silyl{bis-(fluorenyl)}hafnium-dichloride; and

rac-[ethylenebis(2-(tert)butyldimethylsiloxy)indenyl)]-hafnium-dichloride.

A further class of single site catalysts capable of producing highmolecular weight polymers that may be included in the catalyst materialused in the process of the invention are the n-bonding metal complexesof ligands which contain a n-bonding component (e.g. a cyclopentadienylring or an analog such as an indenyl ring) and a component (e.g. a sidechain) capable of co-ordinating to the metal in a non η-bonding fashion.

The metal in such complexes will again conveniently be an ion of a group3 to 6 metal, for example titanium or zirconium. Examples of suchcomplexes include:

1,2,3,4-tetramethyl,5-(dimethylsilyl-{(tert)-butylamido)}(cyclopentadienyl)titanium-dichloride;

1,2,3,4-tetramethyl,5-(dimethylsilyl-{(tert)-butylamido)}(cyclopentadienyl)zirconium-dichloride;and

1,2,3,4-tetramethyl,5-(ethylene-{(tert)-butylamido)}(cyclopentadienyl)titanium-dichloride.

Another class of single site complexes producing high molecular weightpolymers which may be used in the catalyst material comprises compoundshaving one cyclopentadienyl ligand in conjunction with another ligand;e.g. (cyclopentadienyl-hydrido-boro-trispyrazol)-zirconium dichloride.(Other such materials are disclosed in WO97/17379 (Borealis) and thepublications referred to therein).

There are also metal complexes suitable for use as a high molecularweight producing catalyst that do not contain any cyclopentadienylrings; e.g. {3,3′-methoxy,1,1′-(tert)butyl-bi-phenoxy}titanium-di-benzyl.

In general such non ligand containing ligands joined onto the catalyticactive metal through at least one nitrogen atom. Examples of state ofthe art complexes are given in G. G. Hlatky, et al proceedings ofMetallocenes Europe 1998; Schotland Business Research, Inc. USA 1998.

Such complexes containing ligands bound to the catalytic active metalthrough at least one nitrogen atom may optionally contain one or moreligands in addition.

The single site catalyst that can be used in the catalyst material togenerate lower molecular weight components of the overall polymerproduct may conveniently be a metallocene in which the cyclopentadienyl(or equivalent, e.g. indenyl, etc.) groups are not joined by a bridge orwhere the cyclopentadienyl rings are joined by a bridge but the ringpositions adjacent the bridge attachment site are unsubstituted. Againthe metal may be any group III to VI metal, e.g. zirconium. Example ofsuch metallocenes include:

rac-ethylene-bis(1-indenyl)zirconium dichloride;

rac-ethylene-bis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride;

bis(n-butylcyclopentadienyl)zirconium dichloride;

bis(1,2-dimethylcyclopentadienyl)zirconium dichloride;

bis (1,3-dimethylcyclopentadienyl)zirconium dichloride;

bis(4,7-dimethylindenyl)zirconium dichloride;

bis(1,2-ethyl,methylcyclopentadienyl)zirconium dichloride;

bisfluorenylzirconium dichloride;

bisindenylzirconium dichloride;

biscyclopentadienylzirconium dichloride; and

bistetrahydroindenylzirconium dichloride.

All of the complexes mentioned above as suitable for the production ofhigh and low molecular weight components of the overall polymer may beused in conjunction with an aluminoxane. Moreover equivalent complexesin which the halide is replaced by a hydrocarbon ligand (e.g. alkyls,aryls, aralkyls, allyls and alkenyls, e.g. with up to 10 carbons). Inthis case however the complexes need to be activated by a cationicactivator such as a boron compound or an aluminoxane or a mixture ofsuch activators. Alternatively the halides may be replaced by a pendantgroup which also contains an anionic function. In such case thecatalytically active metal is in a cationic form resulting in a complexpresent in a zwitterionic form. Examples of such complexes are given inG. Erker et al, Macromolecules 1997, 30, 3955 and literature citedtherein.

Where an aluminoxane is used, the catalyst material preferably containsa particulate support loaded with the interaction product of the metalcomplex and the aluminoxane.

Ziegler catalysts which may be used for the production of the catalystmaterial are catalysts which normally consist of (i) a transition metalcompound, usually a halogenide, supported on a porous carrier, (ii) ametallorganic co-catalyst where the metal is a group II metal such as Alor B, and (iii) a magnesium compound. Ziegler catalysts are well knownin the art. To produce increasingly higher molecular weight polymers,the transition metal in the Ziegler catalyst can be changed fromtitanium to zirconium to hafnium for example. In general where thecatalyst material used in the process of the invention includes aZiegler catalyst and a single site catalyst, the Ziegler catalyst willfunction to produce the higher molecular weight component of the overallpolymer product.

The different types of catalyst sites in the catalyst material used inthe process of the invention may be present in substantially equalnumbers (ie. a mole ratio of 1:1, or 1:1:1, etc. for two or threecatalyst-type systems). However one catalyst type may be predominantwith other catalyst types being present at a relative mol. % of forexample 1 to 100% (100% representing a 1:1 mole ratio), preferably 5 to80%, especially 10 to 70%.

Generally the quantity of catalyst used will depend upon the nature ofthe catalyst, the reactor types and conditions and the propertiesdesired for the polymer product. Conventional catalyst quantities, suchas described in the publications referred to herein, may be used.

The process of the invention gives rise to polymer products withimproved molecular weight distributions. The advantage of the productsmay be demonstrated by analysis of their rheology. This may be done (asdescribed by Brydson in “Flow properties of polymers”, Iliffe Books,London, 1970) by plotting apparent viscosity P against apparent shearrate 1/s.

The advantage of the products of the process of the invention ascompared with a similar product made in a similar multistage reactorprocess but using just one of the catalysts is that for the productaccording to the invention if it has similar mechanical strength then itwill have improved processability while if it has similar processabilitythen it will have improved mechanical strength.

The process of the invention may be used with particular advantage totailor the distribution of molecular weights in the higher molecularweight fraction of the overall polymer. Moreover this may be done insuch a way as to include comonomer (providing side chains and as aresult increased strength) in the high molecular weight fraction. Thepresence of a bimodal or multimodal distribution at the higher end ofthe molecular weights improves the ease of homogenization as the lowermolecular weight component of the high molecular weight fraction reducesviscosity of the high molecular weight fraction. Without this low end toit the high molecular weight fraction gives rise to melt homogenizationproblems, thereby resulting in an inhomogeneous melt. Using theinvention, the low molecular weight fraction can be produced in thefirst or early stage, conveniently with little or no inclusion ofcomonomer, while a bimodal high molecular weight fraction (with asufficient relatively lower molecular weight component to prevent melthomogenization problems during subsequent processing and with anotherwise unacceptably high molecular weight higher molecular weight,strength giving, component) can be produced, generally with comonomerintroduction, in a second or later stage.

Thus the process allows the user to tailor the placement of comonomerinto the high molecular weight fraction of the polymer and also totailor the molecular weight profile of the high molecular weightfraction of the polymer.

Viewed from a further aspect the invention provides polymers obtained bya polymerization process according to the invention.

The polymers produced using the catalysts or processes according to theinvention have a number of beneficial properties relative to polymersproduced using conventional techniques. In particular, for ethene homoand copolymers, the polymer product preferably has:

1. An extremely high FRR21/2 (ie. the ratio of MFR21 to MFR2). This isof benefit since the high shear viscosity is low. More particularlyFRR21/2 is conveniently at least 160 and more preferably at least 220,e.g. 200 to 450 most preferably above 350. Ethene polymers havingFRR21/2 of 200, preferably 220 to 450 form a further aspect of theinvention.

2. A high activation energy for melt viscosity. This is of benefit as itshows the presence of long chain branching versus conventionalcommercial Ziegler ro chromium oxide made polyolefins, a high shearviscosity reducer. Typically such activation energies may be at least7.5 more preferably at least 8.5 kcal/mol.

3. A higher proportion of the overall polymer is of lower rather thanhigher molecular weight. Typically, the low molecular weight fraction is10-95%, preferably 20-90%, more preferably less than 50% still morepreferably less than 40% and yet still more preferably less than 30% byweight of the overall polymer. This results in an improved balance ofpolymer properties.

4. Where a comonomer, e.g. but-1-ene or hex-1-ene, is used, thisincorporates primarily into the longer rather than the shorter polymerchains so improving the mechanical and processing properties of thepolymer product. Thus the ratio in the short chain branching factor (thenumber of branches (comonomers) per 1000 carbons) between the high andlow molecular weight fractions of the polymer may typically be at least3, preferably at least 5, most preferably at least 15.

5. The polymer product has a high degree of particle to particlehomogeneity. The homogeneity of the polymer is often a matter ofparticular concern to end users since inhomogeniety may give rise tophenomena known as fish eyes, gels or white spots. This is particularlyimportant for films but is also important for wires, cables, blowmoulded products and black pipe.

The production of highly homogeneous multicomponent, e.g. bimodal,olefin polymers in a single polymerization stage has up to now beenproblematical. The use of simultaneous coimpregnation of catalystsupport particles in the process of the invention to produce supportedcatalysts having two or more catalytic sites results in supportedcatalysts which can be used to produce highly homogeneous polymers insingle or multistage polymerizations, particularly highly homogeneousbimodal polymer powders.

Thus viewed from a further aspect the invention provides a polyolefinpowder, preferably an ethene homo or copolymer, comprising at least twopolymer components A and B produced by polymerization catalysed bypolymerization catalysts having at least two different catalytic sites,preferably a supported catalyst comprising both such catalysts, wherecomponent B has a higher weight average molecular weight than componentA and the ratio of the molecular weight of the peak in the molecularweight distribution of component B to that of component A is at least10, preferably at least 15, more preferably at least 20, most preferablyat least 25 and where at least 80 wt %, preferably at least 90 wt % ofthe largest particles (i.e.those in the largest 10 wt % fraction of saidpolyolefin powder) has a S_(log10)M_(W) less than 0.25, preferably lessthan 0.2, most preferably less than 0.15.

Advantageously, the catalysts used should be η-liganded metal complexes,e.g. homo or heterocyclopenta-dienyl liganded complexes as discussedherein. Moreover the proportion of components A and B in the overallpolymer is preferably at least 10 wt % each and at least 80 wt % in sum.Furthermore it is preferred that at least 90 wt % of the polymer isprepared in a single polymerization stage, ie. under essentially similarprocess conditions.

Viewed from a yet still further aspect the invention provides apolyolefin powder, preferably an ethene homo or copolymer, comprising atleast two polymer components A and B produced by a continuouspolymerization process (e.g. a polymerization catalysed bypolymerization catalysts having at least two different catalytic sites,preferably a supported catalyst comprising both such catalysts) wherecomponent B has a higher weight average molecular weight than componentA and the ratio of the molecular weight of the peak in the molecularweight distribution of component B to that of component A is at least10, preferably at least 15, more preferably at least 20, most preferablyat least 25 and where at least 80 wt %, preferably at least 90 wt % ofthe largest particles (i.e. those in the largest 10 wt % fraction ofsaid polyolefin powder) has a S_(log10)M_(W) less than 0.25, preferablyless than 0.2, most preferably less than 0.15.

Such polymer powders have higher homogeneity than powders produced bymixing two separate singly impregnated supported catalyst.

Viewed from further aspect the invention provides a process for thepreparation of such polymers using such catalysts in a single ormultistage polymerization as well as the use of such polymers,optionally after formulation with additives (e.g. filters, colors,antistatic agents, carbon black, stabilizers, antioxidants,plasticizers, etc.) and extrusion and/or grinding and/or pelletization,for the preparation of films, fibres, pipes or moulded products or forcable or wire applications.

Polyolefins prepared according to the invention, preferablypolyethylenes, have a gradient of −0.2 or less, preferably −0.3 or less,especially −0.4 or less, particularly −0.5 or less, e.g. −0.25 to −1.0,in the plot of log apparent viscosity (Pa.s) against log apparent shearrate (s⁻¹) in the range of apparent shear rate from 0.1 to 100 s⁻¹, andpreferably with an apparent viscosity of at least 1000 Pa.s in at leastpart of this range.

Viewed from a still further aspect the invention also provides the useof an olefin catalyst, catalyst activator, or catalyst precursor for themanufacture of a catalyst material comprising a particulate carriermaterial particles whereof carry at least two different types of activepolymerization sites, for use in a process-according to the invention.

All of the documents referred to herein are hereby incorporated byreference.

The invention will now be described further with reference to thefollowing non-limiting Examples.

Parameter Determination

Apparent viscosity vs apparent shear rate was measured on a capilliaryrheometer (Rosend Advanced Rheometer) at 190° C.

MFR's: Melt flow rate (melt index) measured at 190° C. MFR2: with 2.16kg load. MFR5: with 5 kg load. MFR21: with 21.6 kg load.

FRR's: FRR21/2=MFR21/MFR2.

Mw, Mn, MWD: Measured by GPC—Gel permeation chromatography. Mw: weightaverage molecular weight. Mn: Number average molecular weight.

Component peak MW's are found from the MWD curve from GPC.

The MWD from a GPC measurement is by convention presented as a curve ina diagram where:

the abscissa is the log (MW) (MW is molecular weight)

the ordinate is the dW.MW /d(MW)) W is mass or mass fraction of polymer.

At very low and very high MW values, the ordinate value usually is lowor zero. At some intermediate MW thee is at least one maximum point.

A polymer made in one polymerization step under nonchanging processconditions with a catalyst that is not specifically aimed at containingmore than one type of active site, usually makes a polymer with onemaximum only. Usually the distribution then resembles a normal(Gaussian) distribution with a linear (non-logathmic) abscissa. However,when the catalyst system is prepared so that several types of activesites occur giving much different MW's, or the polymerization conditionsis changed in steps so that the steps give very different MW's, thenthis gives rise to more complicated MWD curves with either more than onemaximum or at least one maximum and one shoulder, each maximum and eachshoulder originating from one polymer component as described before. Bystudying such a MWD curve, one can identify the approximate MWD's of thecomponents and estimate each components' approximate maximum. Such amaximum is a component peak MW.

The Slog₁₀M_(W) of the polymer sample is calculated as follows:${{{Slog}_{10}{Mw}} = \sqrt{\frac{\sum\limits_{i = 1}^{n}\quad ( {{\log_{10}{Mwi}} - {\log_{10}{Mwav}}} )^{2}}{n - 1}}}\quad$where  ${\log_{10}{Mwav}} = \frac{\sum\limits_{i = 1}^{n}\quad ( {\log_{10}{Mwi}} )}{n}$

In this equation, M_(wi) is Weight Average molecular weight of the i'thparticle. The total number of particles measured is n.

EXAMPLE 1 Catalyst Preparation

The catalyst was prepared in a glove box into a septabottle. Magneticstirrer was used as a mixer. The following chemicals were used:

0.006 g (n-BuCp)₂ZrCl₂

0.008 g (SiMe₂ (2-Me, 4-Ph Ind)₂ZrCl₂ ^(*)

1.2 ml 30% MAO (Albemarle)

0.3 ml toluene

(n-BuCp=n-butylcyclopentadienyl 2-Me,4-Ph-Ind=2-methyl-4-phenyl-indenylMAO=methylaluminoxane)

* in the rac form

The chemicals were added together and stirred for half an hour.Impregnating was made dropwise on 1.0 g Sylopol 55SJ silica-carrierusing pore filling method. Catalyst was stirred and dried withnitrogen-flow.

Polymerization

Polymerization was carried out in a 2L reactor, 1L isobutane was used asmedium. Polymerization temperature 85° C. and ethylene partial pressure14 bar. Total pressure was maintained at 29 bar.

A multistage polymerization process was effected with polymerization intwo steps:

Step 1 isobutane with 0.18 wt % hexene and ethylene with 2350 ppm H₂;

Step 2 isobutane with 6 wt % hexene and ethylene without H₂.

Catalyst was fed into the reactor with isobutane and the reactor washeated up to the polymerization temperature. Ethylene feeding wasstarted at 75° C. The first step was stopped after 40 minutes byflashing out both isobutane and ethylene. The second step was started byadding isobutane with 6% hexene and then heating it up to the desiredtemperature again. Ethylene feeding was started the same way as instep 1. This polymerization step was effected for 20 minutes and wasstopped by flashing the hydrocarbons out from the reactor.

EXAMPLE 2 COMPARATIVE

The catalyst was prepared according to the procedure of Example 1 usingthe following amount of chemicals:

11 mg (n-BuCp)₂ZrCl₂

1.1 ml 30% MAO (Albemarle)

0.4 ml toluene

1.0 g Sylopol 55SJ SiO2

Polymerization was conducted according to Example 1.

Polymer Product

The apparent viscosity vs apparent shear rate for the products ofExample 1 (diamond) and Example 2 (square) are shown in FIG. 1 of theaccompanying drawings. The apparent shear rate gives an indication atwhat shear rates the product will show unstable flow; the apparentviscosity increases with the molecular weight of the polymer.

EXAMPLE 3 Catalyst Preparation

(A) Sylopol 55SJ (a porous silica from Grace Davison) was calcined at600° C. in dry air for 20 hours. The calcined product has a pore volumeof 1.55 mL/g.

An impregnation solution was prepared by mixing with magnetic stirringat ambient temperature in a small glass vessel in a nitrogen filledglove box:

(nBuCp)₂ ZrCl₂ (ZrA) 17.2 mg

rac-SiMe₂ (2-methyl-4-phenyl-indenyl)₂ ZrCl₂ (ZrB)17.3 mg

MAO solution (30 wt % in toluene, from 2.4 mL Albemarle SA)

Toluene 0.6 mL

Mixing was effected for 30 minutes whereafter the solution was usedimmediately.

20 g of the calcined silica at ambient temperature was placed in a smallglass vessel equipped with a magnetic stirrer. The impregnation solutionwas added dropwise. Stirring was continued for 30 minutes at ambienttemperature until all the solution had been added. With agitation, thevessel was heated to 70° C. and the impregnated silica carrier was driedat 20-5° C. under nitrogen flow for 45 minutes. The volume of solutionadded corresponded to 97% of the carrier's pore volume. By calculationthe supported catalyst product comprised 0.0136 mmol ZrA/g carrier;0.0136 mmol ZrB/g carrier; 5.5 mmol Al (from MAO)/g carrier.

A number of further dual impregnated carriers were prepared analogouslyto Example 3A using varying amounts of MAO, ZrA and ZrB.

(B) A dually impregnated carrier was prepared as in Example 3 A usingtwo separate solutions one containing all the ZrA and half the total MAOand toluene and the other all the ZrB and half the total MAO andtoluene. The solutions were stirred separately for 40 minutes, thenmixed for a short time and then immediately added to the carrier as inExample 3A. ZrA 0.0124 mmol/g carrier, ZrB 0.0124 mmol/g carrier, Al 5.0mmol/g carrier.

(C) A dually impregnated carrier was prepared as in Example 3A. ZrA0.0060 mmol/g carrier, ZrB 0.0180 mmol/g carrier, Al 5.5 mmol/g carrier.

(D) A dually impregnated carrier was prepared as in Example 3A. ZrA0.0170 mmol/g carrier, ZrB 0.0169 mmol/g carrier, and Al 6.8 mmol/gcarrier.

(E) A dually impregnated carrier was prepared as in Example 3A using1.52 mL solution/g carrier, ie. 98% of pore volume. ZrA 0.0171 mmol/gcarrier, ZrB 0.0169 mmol/g carrier, and Al 4.2 mmol/g carrier.

(F) Calcined carrier was wetted with toluene dropwise with stirring tothe level of 0.53 mL toluene/g carrier. Stirring continued for 5 minutesmore. The impregnation solution was then added as in Example 3A, at 1.18mL/g carrier corresponding to a total liquid addition of 110% of porevolume. ZrA 0.0124 mmol/g carrier, ZrB 0.0124 mmol/g carrier, Al 5.5mmol/g carrier.

(G) A singly impregnated carrier was prepared analogously to Example 3Abut using only ZrB. The solution was added at 1 .36 mL/g carrier , ie.to 88as of pore volume. ZrB 0.0248 mmol/g carrier, Al 5.5 mmol/gcarrier.

(H) A singly impregnated carrier was prepared analogously to Example 3Abut using only ZrA. The solution was added at 1.4 5 mL/ g carrier, ie.to 95% and of pore volume. ZrA 0.0240 mmol/g carrier, Al 5.5 mmol/gcarrier.

(I) The calcined carrier of Example 3A was loaded with ZrA and ZrBsequentially. In the first step all ZrA and half the MAO and toluenewere mixed and loaded onto the carrier at 1.50 mL/g carrier (ie. 97%pore volume) as in Example 3A. The loaded carrier was heated and driedas in Example 3A and a second impregnation solution containing all theZrB and half the MAO and toluene was then added as in Example 3A at 1.50mL/g carrier and the product was then again heated and dried as inExample 3A. ZrA 0 .0135 mmol/g carrier, ZrB 0.0135 mmol/g carrier, Al5.5 mmol/g carrier.

(J) A dually loaded carrier was prepared as in Example 3I using only 50%of the MAO solution in each step. ZrA 0.0135 mmol/g carrier, ZrB 0.0135mmol/g carrier, Al 5.5 mmol/g carrier.

EXAMPLE 4 Ethene Polymerization

Using the catalyst of Example 3, ethene polymerization was effected in a2.2L steel reactor fitted with a stirrer an d temperature controlapparatus.

Isobutane, a diluent, 1 liter, optionally containing hex-1-ene, and thecatalyst was charged into the reactor and the temperature and pressurewas then brought up to the desired values. Throughout the reaction runtime, pressure was adjusted by ethene and as ethene was consumed morewas added to maintain the pressure constant. The ethene feed containedsome hydrogen to adjust the molecular weight of the polymer product.After the run time had elapsed, polymerization was stopped by ventingthe overpressure of the reactor.

Under the conditions used, most of the hydrogen added was consumed, andthe amount of hydrogen added thus effectively controlled the polymermolecular weight.

The polymerization process conditions and parameters characterizing thepolymer product are set out in Table 1 below:

TABLE 1 Run 1 2 3 4 5 6 7 8 9 10 [RUN] 21125 21129 21152 21147 2101621035 21144 21148 21048 21044 Catalyst 3A 3A 3A 3A 3B 3C 3C 3C 3C 3DReactor Temperature 87 85 84 85 88 85 84 84 85 85 (° C.) ReactorPressure (bar g) 29 29 29 29 29 22 33 33 29 29 1-Hexene in isobutane 0.20.2 0.2 0.0 0.2 0.2 0.0 0.0 0.2 0.2 (wt %) Catalyst weight (g) 0.0920.065 0.075 0.120 0.085 0.063 0.134 0.150 0.077 0.074 H₂ concentrationin 2240 2240 2240 440 2350 2400 2240 2240 670 2400 Ethene feed (mol/ppm)Run time (min.) 60 60 60 71 61 59 120 80 60 60 Polymer weight (g) 167124 160 282 154 50 141 137 57 60 Yield (g PE/g cat.) 1815 1908 2127 23501812 794 1052 913 740 811 Activity (g PE/g cat./hr) 1815 1908 2127 19861782 807 526 685 740 811 MFR2 0.03 0.05 0.10 — — — — 6.2 — — MFR21 12 2135 0.89 17 1.8 3.2 — 0.4 6.4 FRR21/2 400 420 350 — — — — — — — Density(g/mL) 0.949 0.951 0.955 0.948 0.955 0.940 0.946 0.956 0.941 0.953 Mw(g/mol) — 194000 285000 — 155000 — — — — 250000 Mn (g/mol) — 9000 8000 —9000 — — — — 12000 Mw/Mn — 21 23 — 17 — — — — 20.8 Peak Mw component A —18000 19000 15000 — — — — 17000 (D) Peak Mw component B — 500000 600000400000 — — — — 600000 (D) Ratio peak Mw A:B — 28 32 27 — — — — 35S_(log10)M_(w) 0.12 — — — — — Fraction >0.3 mm (wt %) 65 — — — — 82 No.of particles 9 — — — — — measured Run 11 12 13* 14* 15* 16* 17* 18* 19[RUN] 21052 21051 21003 20993 21061 21046 30092 30091 21053 Catalyst 3E3F 3G 3G 3H 3G + 3H 3I 3J 3D Reactor Temperature 85 85 90 88 88 85 85 8585 (° C.) Reactor Pressure (bar g) 29 29 29 29 29 29 29 29 29 1-Hexenein isobutane 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 (wt %) Catalyst weight(g) 0.110 0.080 0.062 0.094 0.074 2 × 0.038 0.150 0.156 0.088 H₂concentration in 2400 2400 2350 0 2400 2400 2100 2100 2400 Ethene feed(mol/ppm) Run time (min.) 60 59 60 60 60 59 60 60 60 Polymer weight (g)75 88 68 105 216 115 248 249 100 Yield (g PE/g cat.) 682 1100 1097 11172911 1513 1653 1596 1136 Activity (g PE/g cat./hr) 682 1119 1097 11172911 1539 1653 1596 1136 MFR2 0.76 0.06 0.06 — 0.93 23 0.43 17.5 0.01MFR21 67 15.5 9.6 — 14.5 380 60 >400 6.8 FRR21/2 88 258 160 — 16 17 140— 680 Density (g/mL) 0.957 0.954 — — 0.946 0.953 0.954 0.959 0.952 Mw(g/mol) 125000 225000 190000 — — 187000 153000 93000 250000 Mn (g/mol)8000 6900 13000 — — 10000 8500 9600 10000 Mw/Mn 16 33 14.6 — — 18 18 9.721 Peak Mw component A 19000 16000 — — — 25000 23000 25000 18000 (D)Peak Mw component B 350000 500000 90000 — — 450000 350000 400000 600000(D) Ratio peak Mw A:B 18 31 — — — 18 15 16 33 S_(log10)M_(w) — 0.17 — —— 0.48 0.28 0.35 0.06 Fraction >0.3 mm (wt %) — 88 — — — — — No. ofparticles — — — — — 9 — — measured *Comparative Examples

Comparative runs 17 and 18 (catalysts 3I and 3J) have the disadvantagesof requiring extra impregnation and heating and drying steps in thesequential loading of two catalysts onto the carrier. Catalyst 3Imoreover gave rise to fouling in the polymerization run, ie. in contrastto the other runs the polymer particles had clumped together in lumpsand adhered to walls and agitator. Both runs 17 and 18 gave lowerFRR2/21 values than the comparable runs using coimpregnated catalystsystems.

(FRR is a measure of the shear sensitivity of the viscosity from theshear rate. For specific purposes, like HDPE film, the shear sensitivityshould be high. This gives a material that during the film blowingprocess is easy to extrude regarding throughput and has good film bubblestability as well as good mechanical properties of the film.)

EXAMPLE 5 Table of Complexes Used

Complex A=rac-Me₂Silnd₂ZrCl₂

Complex B=rac-Me₂Si(2-Me-4,5-Benzind)₂ZrCl₂

Complex C=rac-Me₂Si(2-Me-4-Ph-Ind)₂ZrCl₂

Table of Examples and Comparative Examples

Hydrogen added in Complexes polymerisation Examples Comparative examplesB + C No hydrogen 5762 GPC results B: 5749; C: 5664 Hydrogen 5761 GPCresults B: 5659; C: 5715 A + B + C No hydrogen 5772 GPC results A: 5571;B: 5749; C: 5664

Catalyst Synthesis Procedure

Work was done under nitrogen atmosphere in a glove box. An amount of35-50 mg of dry complex was added to a toluene solution of methylaluminoxane (MAO), and optionally additional toluene was added. Formulticomplex catalysts, th e individual complexes was dissolvedsuccessively in the same MAO solution. After the complexes) wascompletely dissolved, the solution was added drop by drop to ca. 2 g ofsilica. The volume of solution added did not exceed the pore volume ofthe silica (1.5 to 3 cm³/g). Thereafter the silica powder was stirredfor 15-30 minutes, then nitrogen purged and optionally heated and/orevacuated to remove the toluene. The resulting active catalyst wasstored under nitrogen.

Polymerisation Procedure

A 2L steel autoclave reactor was inerted by heating to ca. 140° C. andnitrogen purged, thereafter cooled to room temperature. Ca. 150 mg ofcatalyst, optionally dispersed in an inert hydrocarbon, was injectedinto the reactor in countercurrent nitrogen flow. Then the reactor wasclosed, and optionally a pressure of hydrogen was added. Finally 1300 mLof liquid propylene was added. The polymerisation temperature was heldat 10-15° C. for 10-15 minutes, then the reactor content was heated to70° C. during ca. 2 min, and maintained at that temperature.Polymerisation was ended by depressuring the reactor. The polymer powderwas dried and weighted.

Table of polymerisation tests Activity Pol run Catalyst H2 Temp TimeAmount [gPP/g M.p. MFR Mw Mn Mw/M no. Date complex [bar] [° C.] [min][g] Cat*hr] [° C.] [g/10 min] [g/mol] [g/mol] n 5761 15/11/96 1 0.11 7045 402 2914 147.3 7.1 410000 115000 3.6 5762 15/11/96 1 0 70 55 390 2144147.3 1 650000 205000 3.2 5772 04/12/96 2 0 70 60 400 1709 146.2 n.a.315000 58000 5.4 5571* 19/02/96 3 0 50 20 70 382 >100 45000 18000 2.55588* 07/03/96 4 0.02 70 35 433 742 134.8 >500 5749* 04/08/96 5 0 70 45n.a. n.a. 4.1 295000 115000 2.6 5732* 04/08/96 6 0 70 30 180 1596 5.45559* 14/02/96 7 0.02 70 90 196 367 144.9 5.0 300000 115000 2.6 5659*10/06/96 8 0.10 70 60 140 1164 230000 95000 2.4 5662* 14/06/96 9 0 70 60350 2069 150.1 0.02 535000 240000 2.2 5715* 13/08/96 10 0.12 70 60 1561040 151.9 28 185000 50000 3.7 5786* 06/11/97 11 0.12 70 65 490 2750151.4 15.5 5664* 17/06/96 12 0 70 60 500 2660 0.04 715000 280000 2.6

Table of catalyst synthesis Amount of Amount Silica ID Pore Finalcatalyst composition Catalyst Complex 30 w % MAO of extra (CalcinedAmount volume of (calc.) ID and amount in toleune toluene in air at ofsilica Toluene Complex [mg] [ml] [ml] 600° C.) silica [cm³/g] Zr w % Alw % w % 1 B + C B: 18 5 0.7 PQ MS3030 1.92 3.1 0.16 (total) 18.2 3.2 C:17 0.084 (B) 0.073 (C) 2 A + B + C 0.15 (total) 13.8 25 A: 14 5 1.7 PQMS3040 2.007 3.3 0.063 (A) B: 24 0.084 (B) C: 13 0.042 (C) 3 A A: 9.19.2 0 Grace 55SJ 5.481 1.6 0.22 13.4 5.2 4 A A: 31.0 3.0 0.5 Grace 55SJ2.00 1.6 0.20 12.0 9.2 5 B B: 16.46 3.1 0 Grace 55SJ 2.00 1.6 0.09 13.50.0 6 B 7 B B: 40 3.0 0 Grace 55SJ 2.00 1.6 0.21 12.6 6.0 8 B B: 25 3.50 Grace 55SJ 2.0 1.6 0.13 14.0 5.4 (500° C. in nitrogen) B: 37.17 3.5 0Grace 55SJ 2.0 1.6 0.19 13.8 6.0 9 C C: 40 n.a. n.a. n.a. n.a. n.a n.a.n.a. n.a. 10 C C: 30.0 3.4 0 Grace 55SJ 2.08 1.6 0.12 11.9 16.7 11 C C:30 3.0 0 Grace 2.0 1.6 0.15 13.0 2.2 sylopol 12 C C: n.a. n.a. n.a. 2104n.a. n.a. n.a. n.a. n.a. n.a

What is claimed is:
 1. A process for the preparation of an olefinpolymer wherein olefin polymerization is effected in a plurality ofpolymerization reaction stages in the presence of an olefinpolymerization catalyst material, wherein said catalyst material isprepared by the simultaneous deposition of a catalyst or catalystactivator and the catalyst material onto a support, said catalystmaterial comprising at least two different types of activepolymerization sites, wherein the catalyst material comprises at leasttwo η-liganded catalysts, wherein each of said η-liganded catalystscomprises a complex of zirconium, hafnium or titanium.
 2. A process asclaimed in claim 1 wherein no one of the reaction stages is used toproduce more than 95% by weight of the overall polymer.
 3. A process asclaimed in claim 2 wherein no one of the reaction stages is used toproduce more than 70% by weight of the overall polymer.
 4. A process asclaimed in claim 1 wherein at least 10% by weight of the overall polymeris produced in each reaction stage.
 5. A process as claimed in claim 1wherein at least two different concentration levels of reactants areused in at least two reaction stages whereby at least one of thecatalytic sites is caused to produce a different polymer in twodifferent reaction stages.
 6. A process as claimed in claim 1 wherein amultiplicity of reactors are used.
 7. A process as claimed in claim 6wherein two reactors are used.
 8. A process as claimed in claim 1wherein said co-catalyst is an aluminoxane.
 9. A process as claimed inclaim 8 wherein said co-catalyst is methylaluminoxane.
 10. A process asclaimed in claim 1 wherein the ratio between the different types ofcatalytic sites is substantially uniform over the support.
 11. A processas claimed in claim 5 wherein a multiplicity of reactors are used.
 12. Aprocess as claimed in claim 5 wherein the ratio between the differenttypes of catalytic sites is substantially uniform over the support. 13.A process as claimed in claim 4 for the copolymerization of ethylene andan α-olefin.
 14. A process as claimed in claim 1 wherein said supporthas a pore volume and said co-catalyst or catalyst activator and saidcatalyst material to be loaded on said support are in a solution whereinthe liquid content of said solution is less than 1.4 times the porevolume of said support.
 15. A process as claimed in claim 14 wherein theliquid content of said solution is less than 1.0 times the pore volumeof said support material.